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Guaifenesin and Creatinine, Urine — Confirmatory Test

Published: August 9, 2026Updated: August 16, 2026

A urine test used to confirm exposure to guaifenesin, an ingredient in some over-the-counter cough and cold medicines. Urine creatinine helps account for differences in urine concentration.

Quick summary

["Detectable guaifenesin supports recent exposure to a medicine containing this cough suppressant."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
87787-8
Short code
guaiFENesin/Creat Ur Cfm
Synonyms
guaiFENesin/Creat Ur Cfm
Category
kidney
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
confirm
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What is this test?

This test measures guaifenesin in urine. Guaifenesin is an expectorant used in some cough and cold medicines, and the urine creatinine measurement helps adjust the result for how concentrated the urine is.

Why might I need this test?

A clinician may order this confirmatory test when medication use or exposure to a cough or cold product needs to be verified. It may also be considered when symptoms could be related to guaifenesin or another ingredient in the same product.

How is the test performed?

A urine specimen is collected and analyzed by the laboratory. The guaifenesin result is evaluated along with the urine creatinine result to help determine the amount present in the specimen.

How do I prepare for the test?

Follow the laboratory or clinician's instructions for urine collection, including any specified timing. Tell the healthcare team about all cough and cold medicines, prescription medications, and supplements you have recently taken.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Detecting guaifenesin in urine indicates that it entered the body, most often through use of a medicine containing guaifenesin. Urine creatinine helps distinguish differences caused by urine concentration, so both results should be interpreted together. A not-detected result does not necessarily exclude earlier exposure because the amount present can change over time.

Short name

Urine guaifenesin confirmation

Frequently asked questions

What is guaifenesin?
Guaifenesin is an expectorant that helps loosen mucus and is found in some over-the-counter cough and cold medicines.
Why is creatinine measured with guaifenesin?
Creatinine reflects urine concentration. Comparing guaifenesin with creatinine helps reduce the effect of variation in urine concentration.
Does a detectable result mean something is wrong?
Not necessarily. It usually confirms exposure to a product containing guaifenesin and should be interpreted by a clinician in the context of your symptoms and medication history.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy